Compressor capacity control



Fell 1967 H. R. WEATHERHEAD 3,303,933

COMPRESSOR CAPACITY CONTROL Filed Jan. 8, 1964 5 Sheets-Sheet 1 Feb. 14,1967 H. R. WEATHERHEAD 3,303,983

COMPRESSOR CAPACITY CONTROL Filed Jan. 8, 1964 5 Sheets-Sheet 3 Feb. 14,1967 H. R. WEATHERHEAD 8 COMPRESSOR CAPACITY CONTROL Filed Jan. 8. 19645 Sheets-Sheet 5 WMW I TTOR/VI/'.

United States Patent 3,303,988 COMPRESSOR CAPACHTY CONTROL Herman R.Weatherhead, Dayton, Ohio, assignor to Chrysler Corporation, HighlandPark, Mich, a corporation of Delaware Filed Jan. 8, 1964, Ser. No.336,543 4 Claims. (Cl. 230-31) This invention relates generally to acompressor and more particularly to means associated therewith forcontrolling the capacity of the compressor in relation to the demandmade upon the compressor.

More specifically the invention relates to novel and improved means foruse with, as for example, reciprocating compressors of the type used inrefrigeration systems, which includes means actuated to hold thecompressor suction valve in an inoperative position during periods ofoperation wherein the compressor is experiencing reduced demands.

An object of this invention is to provide, for a compressor, a novel andimproved compressor unloader arrangement which has the ability to eitherload or unload the compressor in response to small variations in eitherof the control parameters of temperature or pressure.

Another object of this invention is to provide a compressor unloaderarrangement which has the ability to rapidly both load and unload thecompressor without hesitation and without encountering the tendency tocycle and re-cycle as between successive steps of unloading as in acompressor comprised of a plurality of cylinders.

A further object of this invention is to provide a compressor unloaderarrangement which unseats the compressor suction valve in a minimum oftime so as to prevent damage to the suction valve and associatedmechanism, as often occurs in prior art structures, during the period inwhich the suction valve is being lifted or unseated by the associatedunloading mechanism.

Other objects and advantages of the invention will become apparent whenreference is made to the following description and accompanying drawingswherein:

FIGURE 1 is an elevational axial end view of a multiple cylinderreciprocating compressor employing means, constructed in accordance withthe teachings of this invention, for both loading and unloading thecompressor;

FIGURE 2 is an enlarged fragmentary cross sectional View taken generallyon the plane of line 2-2 of FIG- URE l and looking in the direction ofthe arrows;

FIGURE 3 illustrates a fragmentary portion of the cylinder .assembly ofFIGURE 2 operatively connected to an unloader mechanism, constructedaccording to this invention, the fragmentary cross-sectional view ofwhich is obtained by passing a plane through either FIGURES 1 or 2substantially as indicated by line 33 thereon;

FIGURE 4 is an enlarged fragmentary cross-sectional view taken on theplane of line 44 of FIGURE 3;

FIGURE 5 is a view similar to FIGURE 3 illustrating a second embodimentof the invention;

FIGURE 6 is an enlarged fragmentary cross-sectional view taken on theplane of line 6-6 of FIGURE 5;

FIGURE 7 diagrammatically illustrates a multiple cylinder compressor,provided with a capacity control according to this invention, asemployed in, for example, an air conditioning system serving aparticular area;

FIGURE 8 is a simplified schematic wiring diagram illustrating theelectrical circuitry employed for actuation of the compressor capacitycontrol; and

FIGURE 9 is a top plan view of a partial assembly of a particularlysuccessful embodiment of a compressor capacity control arrangement for acompressor having multiple cylinders and in which successive steps ofloading or unloading are desired.

Referring now in greater detail to the drawings, FIG- "ice URE 1illustrates a radial multiple-cylinder reciprocating type compressor 10comprised of a main housing 12 and an end cover assembly 14 securedthereto as by screws 16. A plurality of cylinder assemblies 18 arearranged in a generally radiating fashion from a crankshaft 20, suitablyjournalled within housing 12, and axially spaced therealong.

Cylinder heads 22 close the top of each of the cylinder assemblies 18and may be secured as by screws 24. The compressor discharge chamber 26is separated from the compressor suction chamber 28 by a wall orpartition 30 While a wall 32 separates the suction chamber 28 from thecompressor crankcase chamber 34.

A cylinder liner 36 suitably received within walls 30 and 32 slidablyreceives a piston 38. A connecting rod 40 pivotally secured at one endto piston 38 is provided with a bearing portion 42 at its other endsecured about crankshaft 20. Other connecting rods, having bearings asindicated, for example, at 44, are connected to other pistons comprisingthe compressor 10.

A suction valve 46 located between the top of the cylinder liner 36 anda suction valve plate 48 is normally urged downwardly into seatingengagement with liner 36 by means of a plurality of circumferentiallyspaced suction valve springs one of which is shown at 50.

A suction valve lift ring 52 mounted about cylinder liner 36 and movablerelative thereto engages a plurality of circumferentially spaced,axially directed lift pins biased resiliently downwardly, one of whichis illustrated at 54.

An annular discharge valve 56, contained generally between a dischargevalve cage 58 and suction valve plate 48, is normally urged downwardlyinto seating engagement with suction valve plate 48 by means of aplurality of circumferentially spaced springs, one of which is shown at60, carried generally within valve cage 58. A spring 62 serves tomaintain the discharge valve cage 53, suction valve plate and cylinderliner 36 in assembled relation.

An unloader yoke and body assembly 64, constructed in accordance withthis invention, is mounted on wall 32, generally about cylinder liner 36and below the suction valve lift ring 52. During required intervals ofcompressor operation the yoke and body assembly is caused to lift ring52 in order to move the cooperating abutting pins 54 upwardly therebytemporarily unseating the suction valve 46 and unloading that particularcylinder assembly of the compressor 10.

During loaded operation of the cylinder assembly, every time that piston38 moves downwardly suction valve 46 is moved upwardly off its seatallowing the gas in the suction chamber 28 to pass through a pluralityof intake ports, one of which is shown at 66, and into the interior ofcylinder liner 36. As piston 3-8 is moved upwardly in the compressioncycle, the compressed gas is expelled from the cylinder liner throughports 68 of suction valve plate 48 unseating annular discharge valve 56so as to pass through passageway '70 and into the discharge chamber 26.In a multiple cylinder compressor, as illustrated in FIGURE 1, thesuction chamber 28 and discharge chamber 26, although separated fromeach other, may of course be common to all cylinders as is well known inthe art.

During unloaded operation of the cylinder assembly suction valve 46 ismaintained in an upper position, as a consequence of being lifted bypins 54, thereby causing the gas within the cylinder liner 36 to beexpelled through intake ports 66 back into the suction chamber, everytime that the piston 38 moves upwardly, rather than through thedischarge ports 68.

FIGURE 3 illustrates the unloader yoke and body as sembly 64hydraulically connected, as by means of a suitable conduit 70, to theunloader control assembly 72, which is comprised of a cover 74, solenoidassembly 76, a port plate 78 and valve housing 84). Cover 74, port plate78, housing 80 and seals 82 and 84 located on either side of plate 7 8are preferably secured to each other by means of a plurality of screws86.

Cover 74 carries a valve seat 88, provided with an, annular seal 90, anda tubular valve housing 92 secured to the cover by means of a threadedannular nut 94. A radially extending flange 96 secured to the housing 92as, for example, by brazing, in order to prevent leakage therebetween isheld against a counterbore shoulder of the cover 74 by nut 94.Consequently, the tubular housing 92, which is secured to flange 96, isurged downwardly so as to have its open end 98 held against seat 88 insealing engagement therewith. An annular seal 100 provided betweenflange 96 and cover 74 prevents leakage therebetween.

The upper end of housing 92 is sealingly closed by a plug member 102secured thereto. An axially extending post 104 formed on plug 102carries a flange 106 which serves as an abutment for securing thehousing 108 and coil 110 of solenoid assembly 76 to the tubular housing92. That is, after the tubular housing 92 (and plunger valve 112contained therein) is secured to cover 74 by nut 94, the annularsolenoid assembly 74 is placed over the extending upper end of housing92 and brought into axial abutment with nut 94. Thereafter, a suitablespring clip 114 may be inserted between the upper end of solenoidhousing 108 and the lower surface of flange 106 in order to lock thesolenoid assembly 76 to the tubular housing 92. A spring 115 containedwithin housing 92 and generally between valve 112 and plug 102 normallyurges plunger valve downwardly into sealing engagement with seat 88.

Housing 80 has a cylindrical chamber 116 which slidably receives aregulator valve 118 therein. The innermost end of chamber 116 is incommunication with a conduit 120 while the other end is in freecommunication with the crankcase chamber 34 of the compressor 10. Theregulator valve 118 is preferably formed so as to have an axiallyextending stem-like portion 122 about which a spring 124 is looselyconfined. The spring 124 abuts against an annular spring clip 126 so asto normall urge regulator valve 118 to the left against an abutmentmember 128. Whenever regulator valve 118 is held against stop 128, anannular recess 130 formed in valve 118 is placed in communication withconduit 132. A plurality of radially formed passages 134 completecommunication between recess 130 and an axially directed passageway 136,formed in regulator valve 118, which by virtue of the open end ofchamber 116 is in constant communication with the compressor crankcasechamber 34.

Conduit 138 (formed in cover 74) communicates between chamber 140 (whichgenerally surrounds end 98 of tubular housing 92) and passageway 142 (inport plate 78) which communicates with, for example, the dischargeconduit 144 of a suitable pump 146. Pump 146, as in the case ofhermetically sealed compressors which have their motor sealed therewith,may receive its supply of oil from the compressor crankcase sump asdiagrammatically illustrated at 148. In such situations, the pump 146,which may be conveniently driven by the compressor motor or any othersuitable means, will deliver oil through its discharge passage 144 at apressure which may be some relatively fixed value above suction pressureat which the crankcase chamber normally exists. For convenience thispump discharge pressure will hereafter be referred to as P while the oilsump or suction pressure will be referred to as P The unloader yoke andbody assembly 64 is comprised of a yoke member 150 having arm portions152, generally disposed around the cylinder liner 36, each of which ispivotally mounted on separate pivot members 154 carried by verticallydisposed supports 156. Each of the supports 156 is preferably formedintegrally with a generally semi-circular base portion 158 of the bodyassembly 160 which is removably secured to wall 32 as by means ofsuitable screws one of which is shown at 162.

Body assembly 160 also includes a generally eccentrically disposedcylinder portion 164 containing therein a piston 166 which is preferablyprovided with an annular seal 168. Cylinder 164 is in continualcommunication with conduit 70 as by a coupling-like connector 170secured within wall 32. Connector 170 is provided with an annular seal172, to preclude leakage, and an annular snap-ring-like retainer toprevent accidental downward displacement of the connector relative towall 32.

The terminal ends of arms 152 and base 158 are provided with posts 174and 176, respectively, for receiving thereabout and containing coiledcompression springs one of which is illustrated at 178.

The free ends of arms 152 also have generally spherical portions 180formed thereon which continually abut against the lower surface 182 oflift ring 52. Each of the yoke arms 152 have upwardly directed portions184 which are, in turn, connected to each other by means of anintegrally formed laterally extending bridge portion 186 which alsoserves to carry an axially adjustable abutment screw 188. A nut 190 may,of course, be provided for locking abutment screw 188 to bridge 186.

FIGURE 3 illustrates the cylinder assembly 18 in a loaded condition.That is, means responsive to certain control parameters have caused anelectrical signal to be impressed upon electrical leads or conductors192 and 194 of coil resulting in the ener-gization thereof so as tocause plunger valve 112 to be lifted off of seat 88 against theresistance of spring 115. Consequently, oil at a pressure P flowsthrough passageway 142, conduit 138 and into chamber from where itpasses through ports 196 of tubular housing 92, conduit 198 of seat 88,conduit 200 of cover 74 and into passageway 202 in port plate 78. Frompassageway 262, the oil at a pressure P; is directed into two divergentconduits 204- and 120 (as illustrated iby FIGURE 4). Conduit 204 and therestriction means 206 contained therein will be later referred to ingreater detail.

The oil, under pressure P continues through conduit 120 and into chamber116 forcing regulator valve 118 away from stop 128 to the positiongenerally illustrated in FIGURE 3 thereby causing valve 118 to openconduit 132 permitting oil to flow therethrough and into passageway 208in port plate 8. Passageway 208 extends around passageway 204, so as notto intersect therewith, and communicates with a conduit 210 formed incover 74.

The oil, still at a pressure P flows from conduit 210 through conduit 70and into cylinder 164 ca-using piston 166 and abutment 18 8 to rise. Theupward movement of abutment 188, in turn, causes counter-clockwiserotation of yoke about pivots 154 compressing spring 178 and loweringli-ft ring 52. Consequently, the resiliently biased lift pins movedownwardly allowing suction valve 46 to become seated.

Whenever control parameters indicate that a sufficiently reduced demandhas been placed on the compressor cylinder assembly 18, indiciaresponsive means cause deenergization of coil 110 thereby permittingspring 115 to seat plunger valve 112 in sealing engagement with seat 88terminating the communication of high pressure P therethro-ugh.-Restriction means 206, comprised of a cup-like body portion 212 pressedinto conduit 204, continually bleeds the oil under pressure P through acalibrated orifice 214 to the crankcase chamber 34 which is at a suctionpressure of P Consequently, after plunger valve 112 is seated, the bleedaction of orifice 214 results in a reduction of pressure in chamber 116thereby enabling spring 124 to move regulator valve 118 to the leftterminating further communication between the innermost end 01f chamber116 and conduit 132. When regulator valve 118 abuts against stop 128conduit 132 and annular recess 130 are brought into full registry witheach other causing cylinder 164 of yoke body 160 to be vented to thecrankcase chamber 34 by means of conduits 70, 210, passageway 208,radial passages 134 and axial passage 136.

The venting of cylinder 164 of course causes the pressure of theactuating oil the-rein to decrease permitting spring 178 to rotateunloader yoke 150 clockwise about pivots 154. The rotation of yoke 150,in turn, causes spherical portions 180 of yoke arms 152 to lift thesuction valve lift ring 52 thereby moving pins 54 upwardly unseating thesuction valve 46 and unloading the compressor cylinder assembly 18.

Conduit 204 also contains a filter 216 comprised of porous sinteredbronze which is of a generally hollow truncated conical configuration.The larger diameter of filter 216 is in juxtaposition with the open endof a cuplike body 212 of restriction means 206 while the smaller closeddiameter is disposed upstream thereof. The sum total of the individualareas of all the individual passages for fluid flow through filter 216is considerably greater than the area for fluid flow defined bycalibrated orifice 214. Consequently, the restriction to fluid flowthrough conduit 264 is attributable to only orifice 214 and not thefilter 216. The generally tapered axial wall portion of filter 216permits any foreign particles, which may be carried by the actuatingoil, to be washed to the side of the filter thereby effectivelyincreasing the useful life of the filter as compared to a filter whichwould be placed merely directly across conduit 204 so as to have afiltering area substantially equivalent to the cross-sectional area ofconduit 204.

FIGURES 5 and 6 illustrate another embodiment of the invention. Allelements thereof which are like or similar to those Otf FIGURES 1, 2, 3and 4 are identified with like primed reference numerals.

Referring in greater detail to FIGURES 5 and 6, pump discharge conduit144' supplies actuating oil under a pressure P to a chamber 218, formedin port plate 78', which communicates between conduit 138 in cover 74'and conduit 220 in housing 8%). Whenever regulator valve 118 is moved tothe position illustrated, communication between conduit 226 and aconduit 222 is completed 'by virtue of an axially extending annularrecess or groove 224 formed in the outer cylindrical surface ofregulator valve 118. Conduit 222 is in continual communication at oneend thereof with a passageway 226, in port plate 78', which is formedgenerally about passages 218 and 202 so as not to intersect therewith.Conduit 210, as its counterpart in FIGURE 3, completes communicationbetween passageway 226 and conduit 70' which leads to cylinder 164' Olfthe unloader body 160.

The elements as shown in FIGURE 5 are in positions assumed during loadedcompressor operation. That is, solenoid coil 110' has been energizedcausing plunger valve 112 to become unseated thereby permittingactuating oil, at pressure P to flow through conduits 200', 262, and 120into the innermost end of .cylinder 116 so as to move regulator valve118' against the resistance of spring 124 to the position shown. Duringthe unseated condition of plunger valve 112', oil at P also flowsthrough filter conduit 204, filter 216' and calibrated orifice 214 inthe manner previously described with reference to FIGURE 4.

Whenever the cylinder assembly 18' is to operate at an unloadedcondition, solenoid coil 110 is de-energized permitting spring 115' toseat plunger valve 112. The bleed action of calibrated restriction 214sufficiently reduces the pressure within the innermost end of cylinder116' enabling spring 124 to move regulator valve 118 to the left againststop 128'. Such movement of valve 118 terminates the communicationbetween conduits 220 and 222, previously established by recess 223, andplaces annular recess 130' in registry with conduit 222 so as tocomplete communication between passageway 226 and 6 axial passageway136' which exhausts into the crankcase chamber 34'.

It will become obvious from a comparison of FIG- URES 3 and 5 that thebasic distinction therebetween resides in the solenoid controlledplunger valve and associated conduits. That is, in the arrangement ofFIG- URE 3, all of the oil necessary to accomplish the raising of piston166 must flow through conduit 138, ports 196 and conduits 198. Incontrast, in the arrangement of FIGURE 5, the only quantity of oil whichmust flow through conduit 138', ports 196' and conduit 198 is thatquantity necessary to move regulator valve 118 to the positionillustrated. The oil actually used for raising piston 166' flowsdirectly from passageway 218 through conduits 220, 222 and into conduit70'. In other words, the arrangement of FIGURE 5 is, to a great extent,a servo system with the solenoid-operated plunger valve 112' being thepilot valve and the regulator valve 118' being the slave.

The invention has been thus far disclosed and described in relation to asingle cylinder assembly of a compressor. Nevertheless, it should beapparent that the invention can be practiced equally well in connectionwith a plurality of cylinder assemblies especially Where such amulti-cylinder compressor is to have the capability of stepped orpartial unloading.

For example, FIGURE 7 schematically and diagrammatically illustrates amulti-cylinder compressor 228 with an associated air conditioning system230 serving an area 232. Each of the compressor cylinder assemblies 234is served by a common low pressure or suction manifold 236 by which therefrigerant is returned to the cylinder assemblies and a common highpressure or discharge manifold 238 by which the compressed refrigerantis directed to the condenser 240. The system 230 is also comprised of arefrigerant receiver 242, expansion valve 243 and evaporator 244. Atemperature sensitive member 246 is operatively connected to theunloader control circuitry diagrammatically illustrated at 248 which, inturn, is electrically connected to a plurality (four are illustrated) ofsolenoid assemblies 76 of an unloader control assembly 72'.

FIGURE 8, a simplified schematic wiring diagram, illustrates a motorrelay 250 having conductors 252, 254 and 256 leading thereto from asuitable source of electrical energy and conductors 258, 260, and 262leading therefrom to a motor 264 fordriving the compressor.

A sequential switching device 226 responsive to and actuated by thetemperature sensing bulb 246 of FIG- URE 7, or actuated by a pressuresensing device (not shown) as in the low pressure side of the conduitrycontaining the refrigerant, contains electrical contacts 268, 270, and272 respectively serially connected in conductors 274, 276 and 278.Plunger valve actuating solenoid coils lltba, b, and lltlc arerespectively serially connected, as by their respective terminals 192'and 194', to conductors 278, 276 and 274. Assuming that the compressor,for which the circuitry of FIGURE 8 is intended, is a four cylindercompressor requiring a completely unloaded condition during initialstarting, a fourth unloader control assembly having a plunger valveactuating solenoid coil 110d may be added and serially connected to aconductor 280. It should be noted that each of the conductors 274, 276,278, and 280 are connected in parallel relationship with conductors 282and 284. A time delay switch indicated generally at 286, and comprisedof contacts 287, permits a controlled time delay between starting of thecompressor motor and loading of the compressor. Once contacts 287 close,the particular cylinder assembly controlled by solenoid coil 110'a'will, of course, remain in a loaded condition whereas coils 110a, 110band 110'c, depending upon compressor operating conditions, may be singlyor collectively energized or de-energized in order to satisfy suchoperating conditions.

A control schematically illustrated at 288 as being serially connectedwith conductor 290 is intended to represent all safety controlsincluding such stop and start switches as are appropriate.

The general Operation of the compressor of FIGURE 7, if provided withthe circuitry of FIGURE 8, would be as follows. The start switches incontrol 288 would be closed thereby causing relay 250 to close so as toenergize the compressor motor 264. Simultaneously, time delay switch 286would be energized but contacts 287 would not close until after theexpiration of a predetermined span of time. Consequently, solenoid coils110a, 110b, 110's and lltld would remain in a de-energized conditionthereby resulting in an unloaded condition of each of the cylinderassemblies 234.

After the expiration of a sufficient period of time, contacts 287 oftime delay switch 286 would close causing the energization of solenoidcoil 110d which would result in one of the cylinder assemblies 234operating in a loaded condition. Assuming that the area 232 requiredmaximum cooling, temperature sensing probe 246, which controls theactuation of the sequence switch 226, would have caused contacts 268,270 and 272 to be also closed at the time of the closing of contacts.287. Under such conditions each of the cylinder assemblies 234 wouldhave been placed in loaded condition by the respective solenoid coils.

As the cooling requirements of area 232 decrease, temperature sensitiveprobe 246, at a appropriate instant, causes the opening of, for example,contacts 272 thereby de-energizing solenoid coil 110'a and reducing theoutput of the compressor by one-quarter. If the cooling requirements ofarea 232 still further decrease, temperature probe 246 will again, at anappropriate instant, cause the opening of contacts 270 thereby reducingthe compressor output by another one-quarter so as to have thecompressor operating at half capacity. Similarly, contacts 268 could beopened so as to reduce the compressor to only one-quarter capacity,which, in the particular illustration under consideration, would be theminimum since solenoid coil 110d is not energized or de-energized inresponse to signals generated by temperature probe 246. As alreadyindicated, it should be apparent that a pressure sensing device in thelow pressure side of the conduitry containing the refrigerant could beemployed, in lieu of the temperature probe 246, for controlling sequenceswitch 266.

FIGURE 9 illustrates, in generally plan view, one particularlysuccessful arrangement of a cover, port plate, seals and valve housingwith provision being made therein for the accommodation of a pluralityof solenoidoperated valve assemblies in accordance with the embodimentof the invention as disclosed by FIGURES and 6. The various detailscarried by either the cover, or valve housing, such as the solenoidoperated valve assemblies, the regulator valves are not shown so thatthe conduitry can be better illustrated. Elements in FIGURE 9, which arelike or similar to those of FIG- URES 5 and 6 are identified with likereference numbers sufiixed to identify, where appropriate, multiplicityof such elements. Further, for ease of understanding, each referencenumber will be followed by either a (C), (P) or (H) to designate thatthat particular element is formed in either the cover, port plate orvalve housing, respectively.

Referring now in greater detail to FIGURE 9, fluid under relatively highpressure, supplied as by pump 146' of FIGURE 5, is directed to conduit144' (C) which communicates at its other end with a transverse elongatedmanifold-like supply passage 218 (P) which is in constant opencommunication with vertically disposed conduits 220a (H), 22012 (H),220c (H) and 220d (H). Each of said conduits 220a, 220b, 2200 and 220drespectively communicate with cylindrical chambers 116a (H), 116b (H),116'c (H) and 116d (H) in a manner so as to be in constant communicationwith the annular groove of the regulator valve contained in saidcylindrical chambers as illustrated in FIGURE 5.

Supply passage 218 (P) is also in constant open communication withconduits 138a (C), 138'b (C), 138's (C) and 138'd (C) which have theirother ends in constant open communication with chambers 141M (C), 140%(C), 1400 (C) and 140'd (C). The flow of pressurized fluid from saidchambers 140'11, 140b, 149's and 140d to the vertically disposedconduits 200a (C), 20% (C), 20% (C) and 260d (C), respectively iscontrolled, as illustrated in FIGURE 5, by the plunger valve 112'.Passages 20221 (P), 202'b (P), 202's (P) and 20251 (P) are respectivelyin constant open communication between said conduits 209a, 200b, 200aand 260d and vertically disposed conduits 12022 (H), 12-0'b (H), 1290(H) and 120'd (H) which communicate with said cylindrical chambers116'a, 1161), 116c and 116d as also illustrated in FIGURE 5. Saidconduits 12021, 12012, 120's and 120'd, as previously described withreference to FIGURE 5, provide an avenue of communication forpressurized fluid to enter cylindrical chambers 116a, 11'6b, 116c and116'd in order to actuate the control valves 118' therein.

Vertically disposed conduits 222a (H), 2221) (H), 2220 (H) and 222d (H),which at times are respectively placed in communication with saidconduits 220a, 220b, 22% and 220d by means of groove 224 of controlvalves 118, are in continual open communication with passages 226a (P),226!) (P), 226a (P) and 2260. (P). Said passages 226a, 226b, 2260 and226d are, in turn, in constant communication with conduits 210'a (C),210'b (C), 210c (C) and 210'd (C) which, as illustrated in FIG- URE 5,individually communicate with a suitable conduit such as 70 forsupplying pressurized fluid to piston 164' of each cylinder assembly.

Conduits 204'a (H), 204'!) (H), 204'0 (H) and 204'd (H), which, aspreviously described with reference to FIGURES 5 and 6, continuallypermit some of the relatively high pressure fluid to be bled throughappropriate restriction means, respectively communicate with passages202'a (P), 202'b (P), 202'c (P) and 202'd (P).

The various screws and tapped holes for securing the valve housing seals84' and 82, port plate 78' and cover 74' to each other are notillustrated for purposes of clarity. However, one of the advantages ofthe invention, as will become evident, is the fact that these sameelements can be secured to each as a functioning subassembly prior toinstallation in an otherwise complete compressor. Apertures 292 areprovided in cover 74' in order to accommodate screws for securing thecover, and other elements secured thereto, to housing 12' of thecompressor 10.

The invention as herein disclosed provides an arrangement whereby rapidloading and unloading of the compressor can be accomplished with veryslight changes in temperature (or other indicia of compressor demands).In compressor unloaders of the prior art actuated by suction pressurechange within the compressor, there is of necessity, upon compressorunloading, a sudden surge of suction pressure within the compressor bodywhich causes erratic movement of the unloader regulator between steps ofunloading. This, in turn, causes recycling of the unloader mechanismwhich results in an appreciable span of time before the mechanism andsuction pressure achieve a substantially steady state operatingcondition. This interval of time during which cyclic instability occurs,results in excessive pounding and chattering of the suction valve oftenleading to failure thereof or its associated seat. The invention, inaddition to its ability of rapid loading and unloading, providesstability. That is, the signal generated for initiating the unloading ofany particular cylinder assembly can not be influenced or in any wayimpaired by the accompanying sudden change in suction pressure becauseof the suction pressure per se does not form a link in the circuitry forcausing loading or unloading.

Another important advantage is derived by employing the restrictionmeans 296 and the attendant bleed characteristics. That is, the bleedingaction continually purges the hydraulic circuitry of any refrigerantand/or gas which might become entrained in the oil employed in thehydraulic circuitry.

As previously indicated, the ability of assembling the cover, portplate, valve housing, solenoid operated plunger valve assembly,regulator valve, bleed means and all seals into a totally functioningsubassembly is still another important advantage. This enables thecomplete control to be both hydraulically and electrically tested forthe complete range of anticipated operation and then, without anysubsequent disassembly, mounted on the compressor housing and connectedto the yoke and body assembly 64.

Although only two embodiments of this invention have been disclosed anddescribed it should be apparent that other embodiments and modificationsof the invention are possible within the scope of the appended claims.

I claim: I

1. Unloader means for varying the capacity of a reciprocating compressorhaving a casing, a first partition in the casing for dividing thecompressor into a compression portion and a crankcase portion, a secondpartition means in the compression portion of the compressor fordividing the same into a suction chamber and a discharge chamber, meansforming a cylinder in the compression portion of the compressor, apiston slidably disposed in the means forming a cylinder, a suctioninlet for the means forming a cylinder in communication with the suctionmanifold, a discharge outlet for the means forming a cylinder incommunication with the discharge chamber, suction and discharge valvemeans movably mounted on the suction inlet and discharge outlet tocontrol fluid flow into and out of said cylinder, said unloader meanscomprising an unloader yoke and body assembly, and an unloader controlassembly, said unloader body compris ing a generally semicirculararcuate base portion secured to said first partition so as to be locatedgenerally within said suction chamber and disposed in general straddlingfashion about said means forming a cylinder, pivot support memberscarried by said base in a manner so as to be generally oppositelydisposed about said means forming a cylinder, a second cylinder havingan open end and being carried by said base, a second piston received insaid second cylinder, said yoke comprising arm portions respectivelypivotally supported on said pivot support members so as to generallystraddle said means forming a cylinder, a bridge-like portion connectingsaid yoke arm portions and carrying an adjustably positioned motiontransmitting member, at least one spring contained between said yoke armportions and said base continually urging said yoke to rotate in adirection resulting in said motion transmitting member abutting againstsaid second piston, an annular member closely received about said meansforming a cylinder and being continually urged into engagement with saidyoke arm portions, second means interposed between said annular memberand said suction valve, said unloader control assembly comprising acover member detachably secured to said casing, a port plate secured tosaid cover, a first gasket interposed between said port plate and saidcover, a valve housing secured to said port plate and said valvehousing, a second gasket interposed between said port plate and saidvalve housing, a source of pressurized hydraulic fluid, a cavity formedin said cover, a valve seat having a passageway formed therethroughreceived in said cavity, an elongated valve housing having an open endclosely engaging said valve seat so as to generally circumscribe saidpassageway, a flange carried by said elongated valve housing, meansurging said flange into sealing engagement with said cover, a plungervalve slidably received within said elongated valve housing, a secondspring received within said elongated valve housing continually urgingsaid plunger valve into sealing engagement with said valve seat andpassageway, a first conduit communicating between said source of fluidand said cavity, a second conduit formed in said elongated valve housingenabling communication of said fluid from said cavity to one end of saidpassageway, a third cylinder formed in said first-mentioned valvehousing, a regulator valve slidably received in said third cylinder, agroove formed in the periphery of said regulator valve, a third conduitformed in said regulator valve having one end in open communication withsaid crankcase portion, a fourth conduit formed in said regulator valveinterconnecting said groove and said third conduit, a third springreceived in said third cylinder continually urging said regulator valveinto one of two regulator valve operating positions, a fifth conduitinterconnecting said third cylinder and said passageway, a sixth conduitincluding restriction means interconnecting said crankcase portion andsaid fifth conduit, a seventh conduit interconnecting said thirdcylinder and said second cylinder, said regulator valve being effectiveupon movement by said third spring to said one position to terminatecommunication between said third cylinder and said seventh conduit andto complete communication between said second cylinder, seventh conduit,groove, fourth conduit, third conduit and crankcase portion, andsolenoid means energized in accordance with indicia of compressoroperation for at times moving said plunger valve against said secondspring to permit communication between said passageway and said firstconduit, said hydraulic fluid being effective whenever saidcommunication between said passageway and said first conduit ispermitted to move said regulator valve to the other of said twooperating positions, said regulator valve being effective upon beingmoved to said other operating position to terminate 7 said communicationbetween said seventh conduit and said crankcase and to completecommunication between said fifth conduit and said seventh conduit inorder to admit said hydraulic fluid to said second cylinder to forcesaid second piston to rotate said yoke against the resisting force ofsaid first spring thereby allowing said annular member to move towardsaid base in order to seat said suction valve and load said compressor.

2. Unloader means for varying the capacity of a reciprocating compressorhaving a casing, a first partition in the casing for dividing thecompressor into a compression portion and a crankcase portion, a secondpartition means in the compression portion of the compressor fordividing the same into a suction chamber and a discharge chamber, meansfor forming a cylinder in the compression portion of the compressor, afirst piston slidably disposed in the means forming a cylinder, asuction inlet for the means forming a cylinder in communication with thesuction manifold, a discharge outlet for the means forming a cylinder incommunication with the discharge chamber, suction and discharge valvemeans movably mounted on the suction inlet and discharge outlet tocontrol fluid flow into and out of said cylinder, said unloader meanscomprising an unloader yoke and body assembly, and an unloader controlassembly, said unloader body comprising a generally semicirculara'rcuate base portion secured to said first partition so as to belocated generally within said suction chamber and disposed in generalstraddling fashion about said means forming a cylinder, pivot supportmembers carried by said base in a manner so as to be generaly oppositelydisposed about said means forming a cylinder, a second cylinder havingan open end and being carried by said base, a second piston received insaid second cylinder, said yoke comprising arm portions respectivelypivotally supported on said pivot support members so as to generallystraddle said means forming a cylinder, a bridgelike portion connectingsaid yoke arm portions and carrying an adjustably positioned motiontransmitting member, at least one spring contained between said yoke armportions and said base continually urging said yoke to rotate in adirection resulting in said motion transmitting member abutting againstsaid second piston, an annular member closely received about said meansforming a cylinder and being continually urged into engagement with saidyoke arm portions, second means interposed between said annular memberand said suction valve, said unloader control assembly comprising acover member detachably secured to said casing, a port plate secured tosaid cover, a first gasket interposed between said port plate and saidcover, a valve housing securedto said port plate and said valve housing,a second gasket interposed between said port plate and said valvehousing, a source of pressurized hydraulic fluid, a cavity formed insaid cover, a valve seat having a passageway formed therethroughreceived in said cavity, an elongated valve housing having an open endengaging said valve seat so as to generally circumscribe saidpassageway, a flange carried by said elongated valve housing, threadablemeans urging said flange into sealing engagement with said cover, aplunger valve slidably received within said elongated valve housing, asecond spring received within said elongated valve housing continuallyurging said plunger valve into sealing engagement with said valve seatand passageway, a first conduit communicating between said source offluid and said cavity, a second conduit formed in said elongated valvehousing enabling communication of said fluid from said cavity to one endof said passageway, a third cylinder formed in said first-mentionedvalve housing, a regulator valve slidably received in said thirdcylinder, a first groove formed in the periphery of said regulatorvalve, a third conduit formed in said regulator valve having one end inopen communication with said crankcase portion, a fourth conduit formedin said regulator valve interconnecting said first groove and said thirdconduit, a second groove formed in the periphery of said regulator valvespaced from said first groove, a third spring received in said thirdcylinder continually urging said regulator valve into one of tworegulator valve operating positions, a fifth conduit interconnectingsaid third cylinder and said passageway, a sixth conduit includingrestriction means interconnecting said crankcase portion and said fifthconduit, a seventh conduit interconnecting said third cylinder and saidsecond cylinder, an eighth conduit interconnecting said first conduitand said third cylinder, said regulator valve being effective uponmovement by said third spring to said one position to terminatecommunication between said third cylinder and said seventh conduit andto complete communication between said second cylinder, seventh conduit,first groove, fourth conduit, third conduit and crankcase portion, andsolenoid means energized in accordance with indicia of compressoroperation for at times moving said plunger valve against said secondspring to permit communication between said passageway and said firstconduit, said hydraulic fluid being effective whenever saidcommunication between said passageway and said first conduit ispermitted to move said regulator valve to the other of said twooperating positions, said regulator valve being effective upon beingmoved to said other operating position to terminate said communicationbetween said seventh conduit and said crankcase and to completecommunication between said seventh conduit and said eighth conduit inorder to admit said hydraulic fluid to said second cylinder to forcesaid second piston to rotate said yoke against the resisting force ofsaid first spring thereby allowing said annular member to move towardsaid base in order to seat said suction valve and load said compressor.

3. Unloader means for varying the capacity of a reciprocating compressorhaving a casing, a first partition in the casing for dividing thecompressor into a compression portion and a crankcase portion, a secondpartition means in the compression portion of the compressor fordividing the same into a suction chamber and a discharge chamber, meansforming a cylinder in the compression portion of the compressor, apiston slldably disposed in the means forming a cylinder, a suctioninlet for the means forming a cylinder in communication with the suctionmanifold, a discharge outlet for the means forming a cylinder incommunication with the discharge chamber, suction and dischargeyalvemeans movably mounted on the suction inlet and discharge outlet tocontrol fluid flow into and out of said cylinder, said unloader meanscomprising an unloader yoke and body assembly, and an unloader controlassembly, said unloader body comprising a base portion secured to saidfirst partition so as to be located generally within said suctionchamber and disposed generally adjacent to said means forming acylinder, pivot support members carried by said base in a manner so asto be generally oppositely disposed about said means forming a cylinder,a second cylinder having an open end and being carried by said base, asecond piston received in said second cylinder, said yoke comprising armportions respectively pivotally supported on said pivot support membersso as to generally straddle said means forming a cyhnder, a bridge-likeportion connecting said yoke arm portions and carrying an adjustablypositioned motion transmitting member, at least one spring containedbetween sa d yoke arm portions and said base continually urging saidyoke to rotate in a direction resulting in said motion transmittingmember abutting against said second piston, an annular member closelyreceived about said means forming a cylinder and being continually urgedinto engagement with said yoke arm portions, second motion transmittingmeans interposed between said annular member and said suction valve,said unloader control assembly comprising a cover member detachablysecured to said casing, a port plate secured to said cover, a valvehousing secured to said port plate, a source of pressurized hydraulicfluid, a cavity formed in said cover, a valve seat having a passagewayformed therethrough received in said cavity, an elongated valve housinghaving an open end closely engaging said valve seat so as to generallycircumscribe said passageway, a flange carried by said elongated valvehousing, means urging said flange into sealing engagement with saidcover, a plunger valve slidably received within said elongated valvehousing, a second spring received within said elongated valve housingcontinually urging said plunger valve into sealing engagement with saidvalve seat and passageway, a first conduit communicating between saidcourse of fluid and said cavity, a second conduit formed in saidelongated valve housing enabling communication of said fluid from saidcavity to one end of said passageway, a third cylinder formed in saidfirst-mentioned valve housing, a regulator valve slidably received insaid third cylinder, a groove formed in the periphery of said regulatorvalve, a third conduit formed in said regulator valve having one end inopen communication with said crankcase portion, a fourth conduit formedin said regulator valve interconnecting said groove and said thirdconduit, 9.

third spring received in said third cylinder continually urging saidregulator valve into one of two regulator valve operating positions, afifth conduit interconnecting said third cylinder and said passageway, asixth conduit including restriction means interconnecting said crankcaseportion and said fifth conduit, a seventh conduit interconnecting saidthird cylinder and said second cylinder, said regulator valve beingeflFective upon movement by said third spring to said one position toterminate communication between said third cylinder and said seventhconduit and to complete communication between said second cylinder,seventh conduit, groove, fourth conduit, third conduit and crankcaseportion, and solenoid means energized in accordance with indicia ofcompressor operation for at times moving said plunger valve against saidsecond spring to permit communication between said passageway and saidfirst conduit, said hydraulic fluid being effective whenever saidcommunication between said passageway Y and said first conduit ispermitted to move said regulator valve to the other of said twooperating positions, said regulator valve being effective upon beingmoved to said other operating position to terminate said communicationbetween said seventh conduit and said crankcase and to completecommunication between said fifth conduit and said seventh conduit inorder to admit said hydraulic fluid to said second cylinder to forcesaid second piston to rotate said yoke against the resisting force ofsaid first spring thereby allowing said annular member to move towardsaid base in order to seat said suction valve and load said compressor.

4. Unloader means for varying the capacity of a reciprocating compressorhaving a casing, first partition in the casing for dividing thecompressor into a compression portion and a crankcase portion, a secondpartition means in the compression portion of the compressor fordividing the same into a suction chamber and a discharge chamber, meansforming a cylinder in the compression portion of the compressor, a firstpiston slidably disposed in the means forming a cylinder, a suctioninlet for the means forming a cylinder in communication with the suctionmanifold, a discharge outlet for the means forming a cylinder incommunication with the discharge chamber, suction and discharge valvemeans movably mounted on the suction inlet and discharge outlet tocontrol fluid flow into and out of said cylinder, said unloader meanscomprising an unloader yoke and body assembly, and an unloader controlassembly, said unloader body comprising a base portion secured to saidfirst partition so as to be located generally within said suctionchamber and disposed generally adjacent to said means forming acylinder, pivot support members carried by said base in a manner so' asto be generally oppositely disposed about said means forming a cylinder,a second cylinder having an open end and being carried by said base, asecond piston received in said second cylinder, said yoke comprising armportions respectively pivotally supported on said pivot support membersso as to generally straddle said means forming a cylinder, a bridge-likeportion connecting said yoke arm portions and carrying an adjustablypositioned motion transmitting member, at least one spring containedbetween said yoke arm portions and said base continually urging saidyoke to rotate in a direction resulting in said motion transmittingmember abutting against said second piston, an annular member closelyreceived about said means forming a cylinder and being continually urgedinto engagement with said yoke arm portions, second motion transmittingmeans interposed between said annular member and said suction valve,said unloader control assembly comprising a cover member detachablysecured to said casing, a port plate secured to said cover, a valvehousing secured to said port plate, a source of pressurized hydraulicfluid, a cavity formed in said cover, a valve seat having a passagewayformed therethrough received in said cavity, an elongated valve housinghaving an open end closely engaging said valve seat so as to generallycircumscribe said passageway, a flange carried by said elongated valvehousing, means urging said flange into sealing engagement with saidcover, a plunger valve slidably received within said elongated valvehousing, a second spring received within said elongated valve housingcontinually urging said plunger valve into sealing engagement with saidvalve seat and passageway, a first conduit communicating between saidsource of fluid and said cavity, a second conduit formed in saidelongated valve housing enabling commuication of said fluid from saidcavity to one end of said passageway, a third cylinder formed in saidfirstmentioned valve housing, a regulator valve slidably received insaid third cylinder, a groove formed in the periphery of said regulatorvalve, a third conduit formed in said regulator valve having one end inopen communication with said crankcase portion, a fourth conduit formedin said regulator valve interconnecting said first groove and said thirdconduit, a second groove formed in the periphery of said regulator valvespaced from said first groove, a third spring received in said thirdcylinder continually urging said regulator valve into one of tworegulator valve operating positions, a fifth conduit interconnectingsaid third cylinder and said passageway, a sixth conduit includingrestriction means interconnecting said crankcase portion and said fifthconduit, a seventh conduit interconnecting said third cylinder and saidsecond cylinder, an eighth conduit interconnecting said first conduitand said third cylinder, said regulator valve being effective uponmovement by said third spring to said one position to terminatecommunication between said third cylinder and said seventh conduit andto complete communication between said second cylinder, seventh conduit,first groove, fourth conduit, third conduit and crankcase portion, andsolenoid means energized in accordance, with indicia of compressoroperation for at times moving said plunger valve against said secondspring to permit communication between said passageway and said firstconduit, said hydraulic fluid being elfective whenever saidcommunication between said passageway and said first conduit ispermitted to move said regulator valve to the other of said twooperating positions, said regulator valve being eflective upon beingmoved to said other operating position to terminate said communicationbetween said seventh conduit and said crankcase and to completecommunication between said seventh conduit and said eighth conduit inorder to admit said hydraulic fluid to said second cylinder to forcesaid second piston to rotate said yoke against the resisting force ofsaid first spring thereby allowing said annular member to move towardsaid base in order to seat said suction valve and load said compressor.

References Cited by the Examiner UNITED STATES PATENTS 1,894,267 1/1933Foresman 251-39 2,185,473 1/1940 Neeson 230-30 2,522,762 9/1950 Neeson23031 2,638,265 5/1953 Newton 230-31 2,654,393 10/1953 Ghormley 251302,961,148 11/1960 Courtney 230-31 2,986,368 5/1961 Moore 25130 2,991,9247/ 1961 Ramsay 23030 DONLEY I. STOCKING, Primary Examiner.

MARK NEWMAN, MARTIN P. SCHWADRON,

Examiners. W. I. KRAUSS, Assistant Examiner.

1. UNLOADER MEANS FOR VARYING THE CAPACITY OF A RECIPROCATING COMPRESSORHAVING A CASING, A FIRST PARTITION IN THE CASING FOR DIVIDING THECOMPRESSOR INTO A COMPRESSION PORTION AND A CRANKCASE PORTION, A SECONDPARTITION MEANS IN THE COMPRESSION PORTION OF THE COMPRESSOR FORDIVIDING THE SAME INTO A SUCTION CHAMBER AND A DISCHARGE CHAMBER, MEANSFORMING A CYLINDER IN THE COMPRESSION PORTION OF THE COMPRESSOR, APISTON SLIDABLY DISPOSED IN THE MEANS FORMING A CYLINDER, A SUCTIONINLET FOR THE MEANS FORMING A CYLINDER IN COMMUNICATION WITH THE SUCTIONMANIFOLD, A DISCHARGE OUTLET FOR THE MEANS FORMING A CYLINDER INCOMMUNICATION WITH THE DISCHARGE CHAMBER, SUCTION AND DISCHARGE VALVEMEANS MOVABLY MOUNTED ON THE SUCTION INLET AND DISCHARGE OUTLET TOCONTROL FLUID FLOW INTO AND OUT OF SAID CYLINDER, SAID UNLOADER MEANSCOMPRISING AN UNLOADER YOKE AND BODY ASSEMBLY, AND AN UNLOADER CONTROLASSEMBLY, SAID UNLOADER BODY COMPRISING A GENERALLY SEMICIRCULAR ARCUATEBASE PORTION SECURED TO SAID FIRST PARTITION SO AS TO BE LOCATEDGENERALLY WITHIN SAID SUCTION CHAMBER AND DISPOSED IN GENERAL STRADDLINGFASHION ABOUT SAID MEANS FOR A CYLINDER, PIVOT SUPPORT MEMBERS CARRIEDBY SAID BASE IN A MANNER SO AS TO BE GENERALLY OPPOSITELY DISPOSED ABOUTSAID MEANS FORMING A CYLINDER, A SECOND CYLINDER HAVING AN OPEN END ANDBEING CARRIED BY SAID BASE, A SECOND PISTON RECEIVED IN SAID SECONDCYLINDER, SAID YOKE COMPRISING ARM PORTIONS RESPECTIVELY PIVOTALLYSUPPORTED ON SAID PIVOT SUPPORT MEMBERS SO AS TO GENERALLY STRADDLE SAIDPIVOT SUPPORT A CYLINDER, A BRIDGE-LIKE PORTION CONNECTING SAID YOKE ARMPORTIONS AND CARRYING AN ADJUSTABLY POSITIONED MOTION TRANSMITTINGMEMBER, AT LEAST ONE SPRING CONTAINED BETWEEN SAID YOKE ARM PORTIONS ANDSAID BASE CONTINUALLY URGING SAID YOKE TO ROTATE IN A DIRECTIONRESULTING IN SAID MOTION TRANSMITTING MEMBER ABUTTING AGAINST SAIDSECOND PISTON, AN ANNULAR MEMBER CLOSELY RECEIVED ABOUT SAID MEANSFORMING A CYLINDER AND BEING CONTINUALLY URGED INTO ENGAGEMENT WITH SAIDYOKE ARM PORTIONS, SECOND MEANS INTERPOSED BETWEEN SAID ANNULAR MEMBERAND SAID SUCTION VALVE, SAID UNLOADER CONTROL ASSEMBLY COMPRISING ACOVER MEMBER DETACHABLY SECURED TO SAID CASING, A PORT PLATE SECURED TOSAID COVER, A FIRST GASKET INTERPOSED BETWEEN SAID PORT PLATE AND SAIDCOVER, A VALVE HOUSING SECURED TO SAID PORT PLATE AND SAID VALVEHOUSING, A SECOND GASKET INTERPOSED BETWEEN SAID PORT PLATE AND SAIDVALVE HOUSING, A SOURCE OF PRESSURIZED HYDRAULIC FLUID, A CAVITY FORMEDIN SAID COVER, A VALVE SEAT HAVING A PASSAGEWAY FORMED THERETHROUGHRECEIVED IN SAID CAVITY, AN ELONGATED VALVE HOUSING HAVING AN OPEN ENDCLOSELY ENGAGING SAID VALVE SEAT SO AS TO GENERALLY CIRCUMSCRIBE SAIDPASSAGEWAY, A FLANGE CARRIED BY SAID ELONGATED VALVE HOUSING, MEANSURGING SAID FLANGE INTO SEALING ENGAGEMENT WITH SAID COVER, A PLUNGERVALVE SLIDABLY RECEIVED WITHIN SAID ELONGATED VALVE HOUSING, A SECONDSPRING RECEIVED WITHIN SAID ELONGATED VALVE HOUSING CONTINUALLY URGINGSAID PLUNGER VALVE INTO SEALING ENGAGEMENT WITH SAID VALVE SEAT ANDPASSAGEWAY, A FIRST CONDUIT COMMUNICATING BETWEEN SAID SOURCE OF FLUIDAND SAID CAVITY, A SECOND CONDUIT FORMED IN SAID ELONGATED VALVE HOUSINGENABLING COMMUNICATION OF SAID FLUID FROM SAID CAVITY TO ONE END OF SAIDPASSAGEWAY, A THIRD CYLINDER FORMED IN SAID FIRST-MENTIONED VALVEHOUSING, A REGULATOR VALVE SLIDABLY RECEIVED IN SAID THIRD CYLINDER, AGROOVE FORMED IN THE PERIPHERY OF SAID REGULATOR VALVE, A THIRD CONDUITFORMED IN SAID REGULATOR VALVE HAVING ONE END IN OPEN COMMUNICATION WITHSAID CRANKCASE PORTION, A FOURTH CONDUIT FORMED IN SAID REGULATOR VALVEINTERCONNECTING SAID GROOVE AND SAID THIRD CONDUIT, A THIRD SPRINGRECEIVED IN SAID THIRD CYLINDER CONTINUALLY URGING SAID REGULATOR VALVEINTO ONE OF TWO REGULATOR VALVE OPERATING POSITIONS, A FIFTH CONDUITINTERCONNECTING SAID THIRD CYLINDER AND SAID PASSAGEWAY, A SIXTH CONDUITINCLUDING RESTRICTION MEANS INTERCONNECTING SAID CRANKCASE PORTION ANDSAID FIFTH CONDUIT, A SEVENTH CONDUIT INTERCONNECTING SAID THIRDCYLINDER AND SAID SECOND CYLINDER, SAID REGULATOR VALVE BEING EFFECTIVEUPON MOVEMENT BY SAID THIRD SPRING TO SAID ONE POSITION TO TERMINATECOMMUNICATION BETWEEN SAID THIRD CYLINDER AND SAID SEVENTH CONDUIT ANDTO COMPLETE COMMUNICATION BETWEEN SAID SECOND CYLINDER, SEVENTH CONDUIT,A GROOVE, FOURTH CONDUIT, THIRD CONDUIT AND CRANKCASE PORTION, ANDSOLENOID MEANS ENERGIZED IN ACCORDANCE WITH INDICIA OF COMPRESSOROPERATION FOR AT TIMES MOVING SAID PLUNGER VALVE AGAINST SAID SECONDSPRING TO PERMIT COMMUNICATION BETWEEN SAID PASSAGEWAY AND SAID FIRSTCONDUIT, SAID HYDRAULIC FLUID BEING EFFECTIVE WHENEVER SAIDCOMMUNICATION BETWEEN SAID PASSAGEWAY AND SAID FIRST CONDUIT ISPERMITTED TO MOVE SAID REGULATOR VALVE TO THE OTHER OF SAID TWOOPERATING POSITIONS, SAID REGULATOR VALVE BEING EFFECTIVE UPON BEINGMOVED TO SAID OTHER OPERATING POSITION TO TERMINATE SAID COMMUNICATIONBETWEEN SAID SEVENTH CONDUIT AND SAID CRANKCASE AND TO COMPLETECOMMUNICATION BETWEEN SAID FIFTH CONDUIT AND SAID SEVENTH CONDUIT INORDER TO ADMIT SAID HYDRAULIC FLUID TO SAID SECOND CYLINDER TO FORCESAID SECOND PISTON TO ROTATE SAID YOKE AGAINST THE RESISTING FORCE OFSAID FIRST SPRING THEREBY ALLOWING SAID ANNULAR MEMBER TO MOVE TOWARDSAID BASE IN ORDER TO SEAT SAID SUCTION VALVE AND LOAD SAID COMPRESSOR.